MDM Observatory 2.4m Telescope Observing Report for 2017 Feb 20

Observer(s): Douglas, Nunez, Cortes
Institution(s): Columbia Unviersity

Instrument: ModSpec/Echelle

Worked for 3.5 hours (part of the night)
Conditions were Photometric most of the night.
Problems were encountered, see the separate trouble report for details.

Seeing and Weather:
   High Humidity from 01:00 until 08:00.
   Beg: Clear, Winds Calm
   Mid: Clear, Winds Light & Variable
   End: Cirrus, Winds Moderate

Observing Summary:

Our last night of the run was a tad dramatic. The primary mirror 
started the night below the dewpoint, so we assumed we wouldn't 
be able to observe. After a few hours, though, the humidity fell 
so we were hoping to open. However, the mirror A/C readings were 
haywire (a known issue but we'll also submit a trouble report), 
and we didn't trust whether the primary was actually above the 
dewpoint. Based on conversations with Eric on previous runs, we 
compared the primary mirror temp from the A/C computer to the 
dewpoint on the weather station, and these were too close for 
comfort. The mirror A/C was reading out obviously wrong temps,
but it did give the primary at >~2 deg above the dewpoint. 

Around midnight, Rob Fesen called to let us know he was shutting
down the 1.3m, and he advised us that given the humidity (74% 
and dropping) we could open the mirror and check for condensation. 
Since there wasn't dew anywhere else, we did so - the mirror 
looked fine, so we observed for a few hours. The seeing was OK
and the sky was clear, though we had a few minor pointing issues.  

As our targets got to 2.5ish hours West, we started having 
trouble guiding and our counts were low. We attributed this to 
gusty wind, increasing airmass, and worsening seeing. So we sent 
the telescope and dome home, but the dome only made it to 15 
degrees, instead of going home to 320. It might have been off 
earlier while we were on targets, but we forgot to check. Since 
our targets were heading to high airmass anyway, we decided just
to close for the night.

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Submitted on 2017 Feb 21 [5:46:06]